Conventionally, low volume and mid-volume copiers and image input terminals utilize moving scanning carriages to scan an image, These moving scanning carriages usually include an illumination device like a fluorescent lamp. These scanning carriages are moved across an image by a cable system during the scanning process. Such a prior art scanning carriage system is illustrated in FIG. 1. This scanning system is commonly called a half rate/full rate scanning system.
In FIG. 1, a motor 1 in conjunction with a belt 3 is used to drive a capstan 5. Capstan 5 has a plurality of cable windings around it such that when the capstan 5 is rotated, certain cable strands are pulled onto the capstan and other cable strands are released from the capstan. As illustrated in FIG. 1, two sets of cables 11 and 13 are used to move a lamp carriage 17 and a mirror carriage 19 having corner mirrors 21 positioned thereon.
Cable 11 is connected to the frame 9 by anchor 10. The cable 11 is then wrapped around pulley (roller) 57 and connected to the lamp carriage 17 through clamp 28. From clamp 28, cable 11 is wrapped around pulleys (rollers) 51 and 50 before being wrapped around capstan 5. The remaining portion of cable 11 wraps around pulleys (rollers) 55, 60, 58, and 59 before being connected to spring 8. Spring 8 is connected to the frame 9 by anchor 6. Cable 11 is connected to the mirror carriage 19 at pulleys (rollers) 57 and 58.
Cable 13 is connected to the frame 9 by anchor 2. The cable 13 is then wrapped around pulley (roller) 52 and connected to the lamp carriage 17 through clamp 27. From clamp 27, cable 13 is wrapped around pulley (roller) 50 before being wrapped around capstan 5. The remaining portion of cable 13 wraps around pulleys (rollers) 54, 53, and 56 before being connected to spring 4. Spring 4 is connected to the frame 9 by anchor 6. Cable 13 is connected to the mirror carriage 19 at pulleys (rollers) 52 and 53.
The cables 11 and 13 are wrapped around the pulleys (rollers) in such a configuration that when the cables 11 and 13 are released or pulled onto the capstan 5, the carriages 17 and 19 are properly moved to scan the image. More specifically, a lamp 15 which is located on the lamp carriage 17 provides a light source to scan the image wherein the light reflected from the image is incident upon mirrors located on the lamp carriage 19 and thus are directed toward corner mirrors 21 located on the mirror carriage 19. The corner mirrors 21 direct the reflected light from the mirror on the lamp carriage 19 to a lens. The lens focuses the scanned image onto a CCD or full width array sensor. The sensor converts the reflected light into electrical signals representing the scanned image.
Light reflected from an image as noted above, is incident upon a mirror which is located on the lamp carriage 17. This mirror then directs the light towards the corner mirrors 21 on the mirror carriage 19 which causes the light to make a 180.degree. turn. The light leaving the corner mirrors 21 is directed to an optical lens assembly which focuses the reflected light upon a CCD or full width array sensor.
The utilization of pulleys on the mirror carriage 19 allows the mirror carriage to move into proper proportion to the movement of the lamp carriage 17. In other words, a focused image is maintained by maintaining a certain fixed optical distance between the image 101 and the lens 107 while the lamp carriage 17 is moving. The fixed optical length is ensured by the mirror carriage 19 moving at exactly one half the speed of the lamp carriage 17 and in the same direction as the lamp carriage 17.
As noted above with respect to FIG. 1, the light reflected from the mirror carriage 19 is directed to a CCD sensor which converts the light into electrical signals. The CCD sensor is part of an electronic subassembly of the digital scanner which converts the light into electrical image data in such a form that the image data can be utilized by other devices, such as a workstation or printer to either manipulate the electronic image or print the image onto a recording medium so as to produce a hard copy of the image. The frame of electronic subassembly of a conventional digital scanner is illustrated in FIG. 2.
In FIG. 2, an electronic board 4 is utilized to provide physical support and electrical connections between the various electronic components such as a CCD sensor 3 which are utilized to convert the reflected light of the image into electronic image data that can be utilized by a host device such as a personal computer, computer server, or printer. Since the electronic components of this subassembly produce electromagnetic emissions during their operations, an electromagnetic emission shield 2 ("EME shield") is provided over the electronic circuit boards 4 and the CCD sensor 3 so that the electromagnetic emissions can be confined to the volume within the shield and do not travel to adjacent devices, thereby affecting the electronic operation of these devices.
A significant problem with electronic devices is electromagnetic emissions which can adversely affect adjacent electronic equipment through the generation of unwanted electrical noise in the adjacent device. This is specifically a concern with communication equipment which is very sensitive to stray electromagnetic emissions. Electromagnetic emissions are regulated by government agencies such as FCC in the United States. Thus, to prevent this unwanted emission, conventional digital scanner included the EME shield 2 around the electronic assembly. However, the EME shield 2 also includes an aperture opening 1 which allowed the light reflected from the image to travel unobstructed from the corner mirror to the CCD sensor 3.
A problem associated with this conventional design is that not all the electromagnetic emissions are confined to the volume within the boundaries of the EME shield 3. More specifically, a majority of the electromagnetic emissions from the electronic components of the digital scanner escape through the image aperture opening 1. The electromagnetic emissions which escape through the image aperture opening 1 can then adversely affect the electronic operations of adjacent digital machines. Thus, the image aperture opening 1 within the electromagnetic emission shield 2 diminishes the integrity of the electromagnetic emissions shield 2 such that undesirable electromagnetic emissions escape to the surrounding atmosphere, thereby affecting adjacent digital machines.
Therefore, it is desirable to provide electromagnetic emission shielding for a digital scanner which substantially eliminates the escape of undesirable electromagnetic emissions through the image aperture opening while maintaining an unobstructed optical path between the corner mirror of a half rate/full rate scanning carriage system and the CCD sensor 3.